This invention relates to the generations of electrical power and has particular relationship to radioisotope thermoelectric heat-to-electricity converters and to electrical generators which are called RTG's. RTG's include such heat-to-electricity converters and electrical voltage and/or power converters, DC/DC converters, driven by the heat-to-electricity converters. While this invention has general applicability to RTG's of all types, it is peculiarly advantageous and has unique applicability to RTG's whose power output is in the microwatt or milliwatt range. It is an object of this invention to provide an RTG which shall operate at substantially higher efficiency than prior-art RTG's and shall, at the same time, have smaller dimensions and be of substantially lower cost than such prior-art RTG's.
Typically, microwatt and milliwatt RTG's deliver power of between about 100 microwatts and 100 milliwatts. In the interest of concreteness, the RTG of a heart pacer, or pacemaker, will here be discussed. Such a pacer includes an RTG which delivers about 160 to 170 microwatts at about six volts. In accordance with the teachings of the prior-art, such a pacemaker includes a generator having a heat-to-electricity thermoelectric converter which has an output of several volts and has between a thousand and fifteen hundred thermocouples in series. Each thermocouple is long and its component wires are wound in a spiral or otherwise disposed in layers about the heat source. An electrical converter is driven by this heat-to-electricity converter. While this generator performs satisfactorily, it has a very low efficiency and is of comparatively large dimensions, particularly for insertion in the body of a person. Typically, this pacemaker is of rectangular form, having dimensions of 2.5 .times. 2 .times. 1.3 inches. This pacemaker has an efficiency of only 0.065%.
It is accordingly an object of this invention to overcome the above described disadvantages of the prior-art and to provide a heat-to-electricity thermoelectric converter of substantially higher efficiency than prior-art such converters, and also to provide an RTG including such a heat-to-electricity converter of relatively higher efficiency and smaller dimensions than prior-art RTG's.